Piezoelectric/electrostrictive actuator having ceramic substrate having recess defining thin-walled portion

Abstract

A piezoelectric/electrostrictive actuator including a ceramic substrate (2, 10, 16, 22, 38) and a piezoelectric/electrostrictive portion (26, 28, 29, 30, 33a, 33b, 36a, 36b, 37, 39). The ceramic substrate has at least one recess (6, 14, 20, 24, 42) having a bottom surface which defines a thin-walled portion (8a, 22a), and the piezoelectric/electrostrictive portion is formed on the thin-walled portion of the ceramic substrate.

What is claimed is: 
     
       1. A piezoelectric/electrostrictive actuator comprising: an integrated ceramic substrate   having at least one recess having a bottom surface which defines a thin-walled portion, said thin-walled portion having an average ceramic particle size of 0.1-2 μm; and   a piezoelectric/electrostrictive portion integrated with said thin-walled portion of said ceramic substrate, said piezoelectric/electrostrictive portion being formed on said thin-walled portion by a film-forming process and subsequent heat treatment for integration with said ceramic substrate.   
     
     
       2. A piezoelectric/electrostrictive actuator according to claim 1, wherein said ceramic substrate includes a first layer having at least one opening formed through a thickness thereof, and a second layer which is superposed on and integrated with first layer and cooperates with said at least one opening to define said thin-walled portion. 
     
     
       3. A piezoelectric/electrostrictive actuator according to claim 1, wherein said piezoelectric/electrostrictive portion includes a plurality of films laminated o each other. 
     
     
       4. A piezoelectric/electrostrictive actuator according to claim 3, wherein said plurality of films of said piezoelectric/electrostrictive portion consists of two electrode films, and a piezoelectric/electrostrictive film interposed between said two electrode films 
     
     
       5. A piezoelectric/electrostrictive actuator according to claim 1, wherein said piezoelectric/electrostrictive portion includes a pattern of electrode strips and a pattern of piezoelectric/electrostrictive strips which are formed such that the electrode strips and the piezoelectric/electrostrictive strips are alternately disposed. 
     
     
       6. A piezoelectric/electrostrictive actuator according to claim 1, wherein said piezoelectric/electrostrictive portion consists of a plurality of piezoelectric/electrostrictive units which are formed on said ceramic substrate, such that said units are spaced from each other in a direction parallel to opposite major surfaces of said substrate. 
     
     
       7. A piezoelectric/electrostrictive actuator according to claim 1, wherein said piezoelectric/electrostrictive portion consists of a plurality of piezoelectric/electrostrictive units which are formed on said ceramic substrate such that said units are superposed on each other. 
     
     
       8. A piezoelectric/electrostrictive actuator according to claim 1, wherein said ceramic substrate includes at least one major component selected from the group consisting of aluminum oxide, magnesium oxide, zirconium oxide, aluminum nitride and silicon nitride. 
     
     
       9. A piezoelectric/electrostrictive actuator according to claim 1, wherein said ceramic substrate includes as a major component a zirconium oxide stabilized by at least one compound selected from the group consisting of yttrium oxide, ytterbium oxide, cerium oxide, calcium oxide and magnesium oxide. 
     
     
       10. A piezoelectric/electrostrictive actuator according to claim 1, wherein said thin-walled portion of said ceramic substrate has a thickness not larger than 50 μm. 
     
     
       11. A piezoelectric/electrostrictive actuator according to claim 1, wherein said piezoelectric/electrostrictive portion has a thickness not larger than 100 μm.